Apparatus for optical detection of bio-contaminants

ABSTRACT

A method for optical detection of residual soil on articles (such as medical instruments and equipment), after completion of a washing or a rinsing operation by a washer. A soil detection system provides an indication of soil on the articles by detecting luminescent radiation emanating from the soil in the presence of ambient light.

RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.15/142,309, filed Apr. 29, 2016, which is a continuation of U.S.application Ser. No. 13/777,053, filed Feb. 26, 2013, said patentapplication fully incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the cleaning anddecontaminating arts, and more particularly to a method and apparatusfor optical detection of biological contaminants on articles, such asmedical devices, food, agricultural products, forensic equipment anddevices, and the like, after undergoing a decontamination process.

BACKGROUND OF THE INVENTION

Medical washers are conventionally known and are used to clean articles(e.g., medical devices, such as medical instruments and equipment) thathave been exposed to bio-contaminants. Such washers typically clean thearticles to remove bio-contaminants by directing jets or streams offluid at the articles from spray heads or nozzles located within thewasher. A typical cleaning operation may include a preliminary rinsecycle, a pre-wash cycle, a wash cycle, a post-wash rinse cycle, athermal rinse cycle and a drying cycle. During the rinse and wash cyclesthe articles are exposed to one or more chemical cleaning and rinsingsolutions.

It is not unusual for a cleaning operation to be followed by a visualinspection conducted by a human to insure that there are no residualbio-contaminants (hereinafter referred to as “soil”) on the articles.The soil may include organic residues including, but not limited to,blood, fat, mucous, lipids, carbohydrates, bone, hair, protein, and foodproduct. Some articles have unique shapes, corners or crevices that makeremoval of the bio-contaminants therefrom difficult. Human visualinspection helps ensure that post-wash articles with soil thereon arenot allowed to proceed to further processing (e.g., sterilization)without first removing any remaining bio-contaminants.

As will be appreciated, a human visual inspection is both time-consumingand costly. Moreover, it is difficult to detect minute amounts of soilby human visual inspection, and such visual inspection is subject tohuman error (for example, person-to-person variations and individualbiases). Furthermore, it is observed that human visual inspection is abinary qualitative process, not quantitative.

Some prior art methods for optical detection of soil use a fluorescentdye or agent to detect the presence of soil on an article. In suchsystems, the fluorescent agent is applied to the article, for example,by exposing the article to a solution that includes the fluorescentagent. The fluorescent agent binds to organic residues (e.g., proteins),and thus affixes to the soil to label the bio-contaminant. Where thereis no soil on the article, the fluorescent agent does not become affixedthereto, and thus can be washed off. To provide optical detection of thesoil according to prior art methods, the article is exposed to “blacklight” (i.e., electromagnetic radiation in the ultraviolet range havingwavelengths around 315-400 nm), which is absorbed by the fluorescentagent. Absorbance of this ultraviolet (UV) light causes the fluorescentagent (e.g., a fluorophore such as fluorescein) to emit visible light(i.e., to be fluorescent), thereby identifying the presence of soil to ahuman inspector. A typical human eye is responsive to light in thewavelength range of 390-750 nm.

This prior art method does not allow personnel to carry out their taskof reprocessing of articles in desirable ambient light conditions, andthus makes it difficult for personnel to disassemble, reassemble, andinspect articles for cleanliness. Recommended illuminance levels forsuch work environments can range from 200 lux to 2000 lux, and moretypically range from 1400 lux to 2000 lux.

The present invention provides a method and apparatus for opticaldetection of soil that operates in preferred ambient lightingconditions.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda soil detection system for detecting presence of soil on an article,the soil detection system comprising: (a) a scanning unit including: alight source for producing light to be incident on the article; adetector for detecting electromagnetic radiation emanating from saidarticle and generating light data corresponding thereto, saidelectromagnetic radiation including ambient light reflected by thearticle and light emitted by an excited luminescent agent that is boundto the soil, and a light filter for filtering light of predeterminedfrequencies; and (b) a control unit for receiving the light datagenerated by the detector to determine the presence of soil on thearticle.

According to another aspect of the present invention, there is provideda method for detecting presence of soil on an article, said methodcomprising: introducing a luminescent agent to a detergent during a washcycle of a washing apparatus, wherein the luminescent agent is bound tosoil present on the article; rinsing the article to remove unboundluminescent agent; exposing the article to laser light; detecting lightemanating from said article and generating light data correspondingthereto, said light emanating from said article including ambient lightreflected by the article and light emitted by exciting the luminescentagent bound to the soil; filtering the light emanating from said articleat predetermined frequencies; and determining the presence of soil onthe article based upon the filtered light received by a light detector.

An advantage of the present invention is the provision of a method andapparatus that uses optical excitation and luminescence (such asfluorescence) to detect the presence of soil on articles that haveundergone a washing or rinsing process.

Still another advantage of the present invention is the provision of amethod and apparatus that allows optical detection of soil on articlesin the presence of ambient light.

These and other advantages will become apparent from the followingdescription of the present invention, taken together with theaccompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may take physical form in certain parts andarrangement of parts, preferred embodiments of which will be describedin detail in the specification and illustrated in the accompanyingdrawings which form a part hereof, and wherein:

FIG. 1 is a schematic view of a soil detection system according to afirst embodiment of the present invention;

FIG. 2 is a schematic view of a soil detection system according to asecond embodiment of the present invention;

FIG. 3 is a detailed illustration of a soil detection system accordingto the first embodiment of the present invention;

FIGS. 4A and 4B illustrate internal components of a scanning unit forthe soil detection system;

FIG. 5 illustrates a soil detection system according to an alternativeembodiment of the present invention;

FIGS. 6A is a graph illustrating the intensity of light emitted by anincandescent light bulb for a range of wavelengths;

FIG. 6B is a graph illustrating the intensity of light emitted by afluorescent light tube for a range of wavelengths; and

FIG. 6C is a graph illustrating the intensity of light emitted by acomputer monitor for a range of wavelengths.

DETAILED DESCRIPTION OF THE INVENTION

It should be appreciated that the term “medical devices” as used herein,includes, but is not limited to, such articles as surgical, dental,veterinary and mortuary instruments and equipment. The articles may bemade of various materials, including, but not limited to, stainlesssteel.

Referring now to FIGS. 1 and 3, there is shown a soil detection system30 according to an embodiment of the present invention, generallycomprised of a scanning unit 80 and a control unit 40. Scanning unit 80includes a detector 90, a light source in the form of a laser 100 thatproduces a laser light 102, a light filter 112, and a dichroicbeamsplitter 116 that are located within a housing 81. In theillustrated embodiment, scanning unit 80 is handheld by the user. Itshould be understood that the light source can alternatively be locatedexternal to scanning unit 80 and an optical fiber used to transmit lightfrom the external light source to scanning unit 80.

In the illustrated embodiment, detector 90 takes the form of aconventional digital video/still camera that includes a CMOS(complementary metal-oxide semiconductor) or CCD (charge-coupled device)image sensor 92 and a lens 94. A CCD image sensor 92 represents pixelsby p-doped MOSFET capacitors. These capacitors are biased above thethreshold for inversion when image acquisition begins, allowing theconversion of incoming photons into electron charges at thesemiconductor-oxide interface. Image sensor 92 is then used to read outthese charges. Detector 90 is adapted to detect electromagneticradiation emanating from said articles and generate correspondinginformation (i.e., light data) that is delivered to control unit 40. Itshould be understood that detector 90 may take the form of any suitabledevice able to detect electromagnetic radiation and produce an image,including, but not limited to, a CMOS sensor, a CCD, a photodiode, and aphotodiode array. In the illustrated embodiment, image sensor 92 takesthe form of a color image sensor, such as CCD or CMOS with RGB(Red-Green-Blue) pixel matrix, or a three-dimensional image sensor wherecolor RGB planes are stacked on the same chip, such as 3-CCD or 3-CMOS.These image sensors provide access to each color channel individuallyfor image processing.

In the illustrated embodiment, laser 100 is preferably a laser diodethat predominantly emits light (“laser light”) at a wavelength of 488 nm(blue). As will be explained in further detail below, the laser lightexcites a fluorescent agent (e.g., a fluorophore such as fluorescein).Two- and three-dimensional images may be obtained since fluorescencetakes place in all directions (i.e., the fluorescence signal is usuallyisotropic). Furthermore, the signal-to-noise ratio of the fluorescencesignal is very high, providing a good sensitivity. In the illustratedembodiment, the fluorescent agent is fluorescein, which has a maximumexcitation at light having a wavelength of about 490 nm. Once excited,the fluorescein emits light at a wavelength of about 513 nm. Since theemitted, fluorescent light is of a different frequency than theexcitation light, the excitation light can be filtered out. Theintensity of light emitted from a region having the fluorescent agent iscorrelated to the intensity of excitation energy and to theconcentration of the fluorescent agent.

It should be understood that the light source of the present inventionfor producing light emitted by scanning unit 80 may take a number ofdifferent forms, including, but not limited to, any kind of device beingable to emit a monochromatic or broadband electromagnetic field.Examples of such devices include lasers, solid-state lasers, laserdiodes, argon ion lasers, micro wire lasers, diode solid-state lasers,vertical cavity surface emitting lasers, light emitting diodes (LED),organic light emitting diode (OLED), polymer light emitting diode(PLED), quantum dot based light sources, white light sources, halogenlamps, phosphor-coated LEDs, thin-film electroluminescent devices,phosphorescence OLEDs, inorganic/organic LEDs, LEDs using quantum dottechnologies, LED arrays, flood light systems using LEDs, white LEDs,filament lamps, arc lamps, gas lamps and fluorescent tubes.

Dichroic beamsplitter 116 is used to both reflect and filter light,depending upon the direction the light is traveling toward dichroicbeamsplitter 116. In one direction, dichroic beamsplitter 116 reflectsblue light emitted by laser 100 to direct laser light 102 through anopening 81 a in housing 81. In a second direction, dichroic beamsplitter116 cuts blue light and allows green and red light to pass therethroughfor reception by detector 90. Accordingly, dichroic beamsplitter 116prevents any excitation light (in this case, blue light emitted by laser100) from being received by detector 90. It should be appreciated that acombination of a reflective member (e.g., a dichroic mirror) and one ormore light filters may be substituted for dichroic beamsplitter 116. Inthe embodiment illustrated in FIG. 1, filter 112 is preferably a dualband filter that permits only red and green light to pass therethroughand be received by detector 90.

As shown in FIG. 3, housing 81 includes a handle grip 84. A trigger 86is provided to activate scanning unit 80, as will be explained below. Acable 82 electrically connects scanning unit 80 with control unit 40.

In the illustrated embodiment of the present invention, control unit 40includes a display unit 42 (e.g., an LCD or LED display unit), a userinput interface 44 (e.g., buttons, knobs, keypad, and the like) forcontrol and programming of control unit 40, and an audio output 48(e.g., a speaker) for emitting audible sounds. A power cord 50 connectscontrol unit 40 to a power source (e.g., a conventional AC electricaloutlet). The power source may also supply power to scanning unit 80through control unit 40. Control unit 40 includes a processing unit anddata storage to perform image processing on the light data collected bydetector 90 and provides an audible and/or visual soil detectionfeedback using audio output 48 and display unit 42. A detaileddescription of the operation of control unit 40 and scanning unit 80 isprovided below.

The present invention will now be further described with reference todetection of soil on articles that have been exposed to a solutioncontaining a fluorescent agent (e.g., fluorescein, which isbiocompatible). For example, a medical washer (washing apparatus) may beprovided to remove bio-contaminants from articles placed in a washingchamber by directing jets or streams of fluid at the articles from sprayheads or nozzles located within the washer chamber. The washer may beconfigured to expose the articles to a solution containing thefluorescent agent during the washer's standard wash cycle and/or rinsecycle. The fluorescent agent (non-specifically) binds to organicresidues (e.g., proteins), and thus affixes to soil on the articles tolabel the bio-contaminant. Where there is no soil on the article, thefluorescent agent does not become affixed thereto (i.e., is unbound),and therefore can be easily rinsed off of the article. In a preferredembodiment, no extra wash time is required for labeling thebio-contaminant and no extra rinse time is required to remove all of theunbound fluorescent agent. Accordingly, no changes are required ofexisting medical washers with respect to standard wash and rinse cycles(i.e., no additional “marking” cycle, or pre-wash cycle, etc. isrequired). In one embodiment of the present invention, fluorescein isused as the fluorescent agent at a concentration in the range of about0.001 mM to 90 mM (for example, around 0.3 mM) with an exposure time inthe range of 30 seconds to 5 minutes to label the bio-contaminant.

It is contemplated that the washer may include a source of a fluorescentagent that is introduced into a water inlet line to the washing chamberduring a desired stage of the washing and/or rinsing cycles. A valvecontrols the flow of the fluorescent agent into the water inlet line.Preferably, the solution containing the fluorescent agent is introducedinto the washing chamber during a later stage of the washing cycle.Therefore, during a subsequent rinsing cycle, the fluorescent agent canbe removed from unsoiled portions of the articles. The solutioncontaining the fluorescent agent may be combined with a washing solutionthat includes a decontaminating agent or cleaning detergent. Thedecontaminating agent or cleaning detergent may initially be in a liquidor dry powder form. The fluorescent agent may be directly added to thedecontamination or cleaning detergent before the detergent is added tothe washing chamber.

It should be appreciated that while an illustrated embodiment of thepresent invention is described herein with reference to “fluorescein” asthe fluorescent agent, it is contemplated that alternative fluorescentagents may be substituted for fluorescein. A selected fluorescent agentpreferably has the following properties: approval by governmentregulatory authorities (e.g., FDA); bio-compatible in such a way thatremaining traces of the fluorescent agent on an article can be safelyintroduced into the human body without incurring health problems; bindsrapidly to proteins (e.g., within a few seconds); has the ability towithstand exposure to harsh washing environment conditions (i.e., harshchemicals and temperatures exceeding 80° C.); water soluble; and highquantum yield. Alternative fluorophores include, but are not limited to,rose bengal, acid red, phtalocyanine, and luminol.

While the present invention has been described in connection with theuse of a fluorescent agent, it is also contemplated that the presentinvention may be adapted for use with alternative chemical agents thatprovide luminescence, including but not limited to, chemical agentswhich provide phosphorescence, chemiluminescence, or bioluminescence.

Referring now to FIGS. 1 and 3, one or more articles 10 (e.g., a tool orinstrument) which have been exposed to a solution containing fluoresceinare placed in a tray 5. The articles are preferably arranged in a singlelayer to provide exposure to the light emitted by the light source, aswill be described below.

An operator of soil detection system 30 grabs handle grip 84 to manuallymove scanning unit 80 over the surfaces of an article 10 whileactivating laser 100 using trigger switch 86. Activation of triggerswitch 86 causes laser 100 to produce a laser light 102 at a wavelengthof 488 nm (blue light). The laser light 102 is reflected by dichroicbeamsplitter 116 and travels through opening 81 a of housing 81 and isdirected toward article 10.

Article 10 is exposed to both ambient light and laser light 102 asscanning unit 80 is moved over the surfaces of article 10. FIGS. 6A-6Cshow the intensity of ambient light produced at various wavelengths forambient lighting sources, such as an incandescent bulb, a fluorescenttube light, and a computer monitor screen, respectively. As discussedabove, when the fluorescein that binds to soil is exposed to the laserlight 102 at a wavelength of about 490 nm, the fluorescein emits light(i.e., fluoresces) at a wavelength of about 513 nm.

Reflected ambient light (L_(R)) and fluorescent light (L_(F)) emitted bythe excited fluorescein pass through dichroic beamsplitter 116 andfilter 112 before traveling through lens 94 of detector 90. Filter 112allows only red and green light to pass therethrough to detector 90. Thelight transmitted through lens 94 is received by image sensor 92.

As scanning unit 80 is moved across article 10, the user squeezestrigger 86, thereby activating laser 100 to produce laser light 102 thatis emitted from housing 81 through opening 81 a. Laser light 102 isincident on article 10 as scanning unit is moved across article 10.Ambient light is also incident upon article 10, thereby producingambient light reflections that will include both red and green light.When the fluorescent agent (i.e., fluorescein) present in the soil isexcited by laser light 102 the soil fluoresces thereby emitting light ata wavelength of about 513 nm (green light). Both the reflected ambientlight (L_(R)) and the fluorescent light (L_(F)) of the soil pass throughfilter 112 which filters out all but red and green light. Therefore,image sensor 92 only receives red and green light.

Referring now to FIG. 1, there is shown a sample input spectrum 120. Asscanning unit 80 is moved across article 10, image sensor 92 acquiresand transmits to control unit 40 detected light data indicative of inputspectrum 120 that includes a green light waveform 122 and a red lightwaveform 124. Green light waveform 122 is indicative of the intensity ofgreen light detected by image sensor 92 and red light waveform 124 isindicative of the intensity of red light detected by image sensor 92.

Control unit 40 is programmed to spectrally discriminate between soilfluorescence (indicating the presence of soil) and specular ambientlight reflections, based upon the measure of saturation of green lightintensities relative to red light intensities (ratio). In theillustrated embodiment, the range of this measure of saturation isenclosed between zero and one. Accordingly, the system is robust to thevariations of ambient light of the surrounding environment and changesof acquisition parameters. A value of saturation close to zero isindicative of the presence of specular ambient light reflections,whereas a large value close to one is indicative of the presence ofsoil.

Control unit 40 may be programmed to display the detected light data toa user on display unit 42. Control unit 40 may also be programmed toprovide the user with a visual and/or audible indicator (e.g.,warning/alarm/feedback) via display unit 42 and audio output 48 in theevent that the ratio of green light intensity-to-red light intensityindicates the presence of soil. It is further contemplated that controlunit 40 may present an image of article 10 and use display unit 42 todisplay the location of the detected soil (i.e., contaminated region) onarticle 10. The image of article 10 may be acquired during opticalscanning of article 10 or from a prestored image library comprised ofimages of a plurality of commonly used articles 10.

Referring now to FIG. 2, there is shown a soil detection system 30Aaccording to an alternative embodiment of the present invention. Soildetection system 30A is similar to soil detection system 30 in severalregards, and thus like components have been given the same referencenumbers. Soil detection system 30A includes scanning unit 80A havinglaser 100, detector 90, a power modulator 34, dichroic beamsplitter 116,and a light filter 112A that allows only green light to passtherethrough. Power modulator 34 produces a pulsed waveform thatprovides an ON/OFF signal to activate/deactivate laser 100. When thepulse is an ON signal, laser 100 is activated to produce laser light102. The pulsed waveform causes laser 100 to be continuously pulsed ONand OFF at a laser modulation frequency. As scanning unit 80A is movedacross article 10, the user squeezes trigger 86, thereby activatingpower modulator 34 to produce the pulsed waveform that provides theON/OFF signal to laser 100. When the pulse is an ON signal, laser light102 is emitted from housing 81 through opening 81 a. It should beappreciated that power modulator 34 may alternatively take the form of asquare wave modulation circuit to modulate the output of laser 100(amplitude modulation).

Laser light 102 is incident on article 10 as scanning unit is movedacross article 10. Ambient light is also incident upon article 10,thereby producing ambient light reflections that will include greenlight. When the fluorescent agent (e.g., fluorescein) present in thesoil is excited by laser light 102 the soil fluoresces thereby emittinglight at a wavelength of about 513 nm (green light). Both the reflectedambient light (L_(R)) and the fluorescent light (L_(F)) of the soilpasses through filter 112 which filters out all but green light.Therefore, image sensor 92 only receives green light. In thisembodiment, image sensor may take the form of a color or gray-scale typesensor.

The modulation frequency for laser 100 is set to be lower than theemission frequencies of ambient lighting sources. Detector 90 operatesin a continuous (video) mode at a frame rate that is higher that themodulation frequency. Green blinking features on display unit 42 ofcontrol unit 40 at the modulation frequency are indicative of soil.Non-blinking features or blinking at frequencies other than themodulation frequency are identified as ambient light reflections. In oneembodiment of the present invention the modulation frequency is around10 Hz. The frequency of ambient lighting sources are f=20-60 kHz(electronic ballast fluorescent tube), f=120 Hz (incandescent light bulband magnetic ballast fluorescent tube), and f=240 Hz (computer monitor).

As scanning unit 80A is moved across article 10, power modulator 34produces the pulsed waveform that causes detector 90 and laser 100 to becontinuously pulsed ON and OFF. As indicated above, filter 112A onlyallows green light to pass therethrough to detector 90. Image sensor 92acquires and transmits to control unit 40 detected light data indicativeof the intensity of green light detected by image sensor 92.

FIG. 5 illustrates a soil detection system 30B according to analternative embodiment of the present invention. Soil detection system30B includes a control unit 40A having an inspection chamber 60 forinspecting articles 10 placed on a tray 5. A plurality of scanning units80B are located within chamber 60 for exposing the plurality of surfacesof an article 10 to laser light 102. Scanning units 80B are similar inmost respects to scanning units 80 and 80A except that they areautomatically activated by control unit 40A. The embodiment shown inFIG. 5 eliminates the need for the user to manually activate a handheldscanning unit 80, 80A and manually expose all of the surfaces of anarticle 10 to laser light 102.

It is contemplated that tray 5 may also be connected with an apparatus(now shown) for rotating, shaking, or otherwise moving tray 5 withinchamber 60. It is further contemplated that scanning units 80B may bemounted to moveable arms (not shown) to provide a range of motion foreach scanning unit 80B. Control unit 40 is programmed to controlmovement of tray 5 and scanning units 80B.

The foregoing description discloses specific embodiments of the presentinvention. It should be appreciated that these embodiment are describedfor purposes of illustration only, and that numerous alterations andmodifications may be practiced by those skilled in the art withoutdeparting from the spirit and scope of the invention. For example, it iscontemplated that the scanning unit of the present invention couldcommunicate with the control unit via wireless communications. It isalso contemplated that the method and apparatus of the present inventionmay also be used in combination with automated and human visualinspections using “white light” imaging. In addition, it is furthercontemplated that the present invention may be adapted to include afiber optic accessory for point inspection of canulated instruments. Itis intended that all such modifications and alterations be includedinsofar as they come within the scope of the invention as claimed or theequivalents thereof.

Having described the invention, the following is claimed:
 1. A soildetection system for detecting presence of soil on an article, the soildetection system comprising: a scanning unit for scanning the articlewith a fluorescent agent bound to soil present on the article, thefluorescent agent emitting fluorescent light at a fluorescencewavelength, wherein the scanning unit is moved across a surface of thearticle, said scanning unit including: a light source for producing alaser light blinking at a modulation frequency to be incident on thearticle, wherein the modulation frequency is lower than a blinkingfrequency of an ambient lighting source, a light filter for filteringlight emanating from said article at the fluorescence wavelength, saidlight emanating from said article including ambient light from theambient lighting source reflected by the article and light emitted byexciting the fluorescent agent bound to the soil with the laser light,and a light detector for detecting the filtered light emanating fromsaid article and generating light data corresponding thereto; and acontrol unit for receiving the light data generated by the lightdetector to determine the presence of soil on the article based upondetection of blinking features at the fluorescence wavelength determinedto be blinking at the modulation frequency and indicative of soil,compared to detected features at the fluorescence wavelength that arenon-blinking at the modulation frequency and identified as ambient lightreflections, thereby discriminating between soil fluorescence andambient light reflections.
 2. A soil detection system according to claim1, further comprising a power modulator to produce a pulsed waveformthat causes the laser light produced by the light source to becontinuously pulsed ON and OFF at the modulation frequency.
 3. A soildetection system according to claim 1, wherein the fluorescencewavelength is green light, and wherein said light filter permits onlygreen light to pass therethrough and be received by said light detector.4. A soil detection system according to claim 1, wherein the fluorescentagent is fluorescein that binds to soil and fluoresces under the laserlight at a fluorescence wavelength of about 513 nm.
 5. A soil detectionsystem according to claim 1, wherein the laser light is at a wavelengthof about 490 nm, an excitation wavelength upon which the fluorescentagent emits the fluorescent light.
 6. A soil detection system accordingto claim 1, wherein said scanning unit includes a dichroic beamsplitterthat reflects the laser light produced by the light source and passesreflected ambient light and emitted fluorescent light.
 7. A soildetection system according to claim 1, wherein said scanning unitcomprises a handheld scanning unit.
 8. A soil detection system accordingto claim 7, wherein said handheld scanning unit comprises a handle gripgrabbed by a user to manually move the handheld scanning unit across thesurface of the article, and a trigger switch to activate the lightsource of the handheld scanning unit.
 9. A soil detection systemaccording to claim 1, wherein the scanning unit comprises a plurality ofscanning units located within a chamber for exposing a plurality ofsurfaces of an article to the laser light.
 10. A soil detection systemaccording to claim 9, wherein the plurality of scanning units areautomatically activated by the control unit.
 11. A soil detection systemaccording to claim 9, further comprising a tray for receiving thearticle, wherein the tray is moveable within the chamber with respect tothe plurality of scanning units.
 12. A soil detection system accordingto claim 9, wherein the plurality of scanning units are moveable toprovide a range of motion with respect to the article.
 13. A soildetection system according to claim 1, wherein the modulation frequencyof the light source is about 10 Hz.
 14. A soil detection systemaccording to claim 1, wherein the blinking frequency (f) of the ambientlighting source is selected from at least one of: f=20-60 kHz for anelectronic ballast fluorescent tube light source; f=120 Hz for anincandescent light bulb and magnetic ballast fluorescent tube lightsources; or f=240 Hz for a computer monitor.
 15. A soil detection systemaccording to claim 1, wherein the light detector operates in acontinuous video mode at a frame rate that is higher than the modulationfrequency.
 16. A soil detection system according to claim 2, wherein thepower modulator comprises a square wave modulation circuit that causesthe light source to implement amplitude modulation of the laser light atthe modulation frequency.
 17. A soil detection system for detectingpresence of soil on an article, the soil detection system comprising: aplurality of scanning units located within a chamber for scanning aplurality of surfaces of the article having a fluorescent agent bound tosoil present on the article, the fluorescent agent emitting fluorescentlight at a fluorescence wavelength, each of said plurality of scanningunits including: a light source for producing a laser light blinking ata modulation frequency to be incident on the article, wherein themodulation frequency is lower than a blinking frequency of an ambientlighting source, a light filter for filtering light emanating from saidarticle at the fluorescence wavelength, said light emanating from saidarticle including ambient light from the ambient lighting sourcereflected by the article and light emitted by exciting the fluorescentagent bound to the soil with the laser light, and a light detector fordetecting the filtered light emanating from said article and generatinglight data corresponding thereto; and a control unit for receiving thelight data generated by each light detector of the plurality of scanningunits to determine the presence of soil on the article based upondetection of blinking features at the fluorescence wavelength determinedto be blinking at the modulation frequency and indicative of soil,compared to detected features that are non-blinking at the modulationfrequency and identified as ambient light reflections, therebydiscriminating between soil fluorescence and ambient light reflections.